Question

I’m trying to pass the following structure through c++ DLL to c#:

struct name 
{   char* myArray[3];
    char firstname[100]; 
    char lastname[100]; 
}; 

void Caller(struct name * demo) 
{
  strcpy(demo->firstname,"hello");
  demo->myArray[0]="hello";
  demo->myArray[1]="hello";
  demo->myArray[2]="hello";
  ping(demo);                     //call to c# function
}

Below is my c# code:

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public struct name
{
   [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 100)]
   public string firstname;
   [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 100)]
   public string lastname;

   //what should i marshal here for  char* myArray[3];
} ;

static void Main(string[] args)
{
   name myname = new name();
   ping( ref myname);
}

public static void ping(int a,ref name myname)
{
   Console.WriteLine(myname.firstname+"\n");
}

I am able to import first and last name from c++ dll.

What should I do to import char pointer array form c++?

Answer 1

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public struct Name
{
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 100)]
    public string FirstName;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 100)]
    public string LastName;
    [MarshalAs(UnmanagedType.ByValArray, SizeConst = 3)]
    public string[] Array;
};

for my complete solution check Foo.cpp and Program.cs: https://gist.github.com/3779066